Through the efforts of numerous laboratories, including this, the pathogenesis of hyperthyroidism of Graves' disease is now recognized as based on the action of a thyroid-stimulating (auto) antibody, TSAb. That being reasonably well established future problems include the following: 1. Is the thyroid antigen homologous to TSAb identical with the receptor for thyrotropin? To answer this question receptor will be purified by affinity chromatography and its interaction with TSAb studied. Secondly, soluble preparations of surface-labeled thyroid cells will be used to overlay either thyrotropin or TSAb that has been subjected to isoelectric focusing in polyacrylamide gel; subsequent autography of washed gels will be carried out. Thirdly, purified receptor for thyrotropin will be used to immunize animals for subsequent testing of the antisera as thyroid stimulators. 2. Specific gangliosides bind thyrotropin; a unique possibly fucosyl ganglioside, is said to occur in the membrane of the thyroid gland and there may be others specific to Graves' disease thyroid. Purified gangliosides (e.g. GT1, TDIb) will be used to prepare an adsorbent for thyrotropin and then used to test the binding of TSAb. If the specific Graves' disease ganglioside can be isolated it will similarly be tested for binding to thyrotropin and TSAb. As a tangential project, gangliosides of thyroid from rats fed control or goitrogenic diet will be extracted and compared by thin-layer chromatography; is it possible that there is a qualitative change in membrane gangliosides associated with chronic stimulation? 3. TSAb is an IgG of restricted heterogeneity as judged by our studies using isoelectric focusing. It therefore may be feasible to use it as antigen to raise an anti-idiotype antibody and thus develop a radioimmunoassay for TSAb. The hoped-for antigen will be purified by adsorption to and desorption from human liver and then human thyroid, followed by chromatography to isolate it as a group specific IgG.